Can You Make Your Own Travel Payment Device?

Stories of people removing the chip from Oyster cards and inserting it into key-rings, bracelets and other non-card objects have been knocking around for years. Now that contactless payment is being rolled out, we decided to take a look at the possibilities.

We asked Transport for London (TfL) for its views on putting chips into other objects and were told 'they are not accepted on the network as a valid form of payment':

“By defacing Oyster cards and then travelling with them people would be risking a penalty fare as passengers need to produce a valid, intact ticket when requested. Plus they would not be able to hand back only part of a card and be reimbursed the deposit or any value that remains the card.”

So that's that then. Or is it?

You might not be allowed to put your Oyster chip in something else, but what about making your own device which reads the data on your Oyster card? We asked an expert and (unsurprisingly) it's more complicated than it might seem. Like contactless cards — hence the relentless warnings about card clash — Oyster cards use radio-frequency identification (RFID) technology which means you need a chip in another object, such as a rubber chicken. So, you pop an RFID chip into your rubber chicken (there's a phrase we don't expect to use often). It will then need to interact with the chip in the Oyster card.

Assuming all your user data is stored in a central database in the bowels of TfL's headquarters, you can have as many rubber chickens as you like linked to your Oyster card. You could even enter a station using the conventional method and exit using a rubber chicken and your journey would be recorded seamlessly. You might look a bit of a tit though.

The problems arise when user data is stored on the Oyster chip itself. We freely admit that we have no idea if this is the case or not. If it is, you would need to synchronise the chip in the chicken with the chip in the Oyster card. Inevitably, this could be done via a smartphone app or even using a kiosk in the station.

Keen-eyed readers will have spotted the potential pitfall of the RFID rubber chicken straight away. Oyster software and encryption is proprietary to TfL, so unless they agree to allow you to interact with their software, you're stuck with your card. We asked TfL if they were working on any projects to pair Oyster cards with other devices and the answer was no. It also told us it has no plans to do so.

Alternatively, you could make your own contactless payment device. Because the card belongs to the bank, not TfL, you don't run the risk of being charged with hacking offences for fiddling with their data. If you can work out where in the card the contactless chip is located, in theory you could remove it and put it in any object you like though obviously this would make the card itself useless.

Contactless payment wristbands using a chip are being trialled, though just Barclaycard in the UK have them so far. It's likely we'll see similar bracelets from other banks. Event organisers have also discovered the uses of RFID and there are companies which produce wristbands for entry and cashless payment at festivals.

Wristbands would at least minimise the chances of card clash, though if you leave it in your bag until you get to the barrier, you're still going to piss off everyone behind you.

for about 20 years. It's an RFID chip embedded in a tiny keyfob. It's used to purchase fuel in the USA and Canada from major retailers. So I have been successfuly using a contactless payment system for all those years. It is linked in my case to a credit card, so I have an addiional level of security (in that both the device provider and my bank run fraud protection).

I've also had a US-bank contactless debit card for almost ten years, and I recall them being trialled over 20 years ago in San Francisco. The problem is getting people to use them and with designing a reliable system (Oyster and UK banks have a way to go yet).

Andy Brice

Some data is stored on the Oyster card itself, yeah. That's how buses are able to know your balance without connecting to the internet to check. And why you have to nominate a station to "collect" tickets and credit you buy online.

Andy Brice

If you want to reverse-engineer an RFID card, you'll need an antenna as well as the chip. You can dissolve the whole card in acetone to remove these components.